The present invention relates to a high voltage pulse generation device for a magnetron. The high voltage pulse generation device comprises a power supply in which a high voltage pulse is super-positioned onto the DC voltage, wherein the magnetron is driven by generating a high voltage pulse using a pulse transformer and a resonance circuit.
A conventional high voltage pulse generation device is constructed in such a manner that a high pulse is generated by switching a DC power supply using a thyristor diode module (hereinafter TDM) and by having a resonant circuit at the TDM output.
A high voltage is applied to the TDM output because the TDM output is directly applied to the load via the resonant circuit. This is a disadvantage in that the cost of the device is increased due to the high voltage rating required of all the components in the circuit.
Therefore, the present invention relates to providing a relatively inexpensive high voltage pulse generation device by using a low voltage circuit to generate high voltage pulses.
Further, the present invention relates to providing a high voltage pulse generation device having reduced insulation space requirements and reduced weight.
To overcome the defects of the prior art, the high voltage pulse generation device of the present invention is constructed in such a manner that a high voltage switch is placed at the primary side of a transformer, a resonant circuit is constructed from components on the primary and secondary sides of the transformer, with a high voltage pulse being applied to the load at the secondary side of the transformer.
More specifically, the circuit presented herein is divided into two parts, which respectively generate different types of voltages. A first DC voltage generation part continuously applies a variable DC voltage at a required value to the load. A second pulse voltage generation part generates a momentary high voltage pulse and supplies the same to the load. The voltage applied to the load is the super position of the output voltages of the two parts. The circuit also includes a pulse transformer demagnetization power supply, which is constructed separately from the pulse voltage generation part, and which resets the pulse transformer core flux after pulse generation.
A high voltage pulse generation circuit is usually constructed with a resonant circuit and a high voltage switching arrangement. However, present invention generates a high voltage pulse waveform through a pulse transformer and momentary resonance by using low voltage pulse generator, which results in a different resonant circuit construction. Because of the low voltage components, the required insulation space is reduced thereby reducing the size and the weight of the circuit as compared with conventional circuits. Further, when necessary, the pulse generation circuit can adjust the peak value, number of the pulses, and the DC voltage applied to the load. The pulse width and other pulse parameters may be varied by adjusting the component values in the design of the circuit. Additionally, a thyristor diode module is used as a semiconductor switching element for resonance generation, which simplifies the control and system construction resulting in manufacturing advantages.
The power supply for the high voltage pulse generator is a DC voltage obtained by rectification from an AC power supply. The resonant circuit is constructed by connecting a resonant inductor to the primary side of a high frequency transformer and a resonant capacitor to the secondary side. The resonance current begins to flow as the thyristor of the TDM cycled at the design frequency. A separate complex switching operation is not required because of the backward flow of current through the diode of the TDM from the moment that the resonance current changed.
The pulse transformer demagnetization power supply controls the residual magnetism of the pulse transformer after a pulse generation, preventing saturation of the pulse transformer.
To switch a high voltage, several elements must be connected in series because of the limited voltage and current rating of the elements. In the present invention, several TDMs are serially connected, each TDM consisting of a thyristor and a diode connected in anti-parallel. Further, the DC base voltage applied to the load is supplied by a separate variable DC power supply circuit.